Semiconductor fabrication processes are typically conducted with the substrates supported within a chamber under controlled conditions. For many purposes, semiconductor substrates (e.g., wafers) are heated inside the process chamber. For example, substrates can be heated by direct physical contact with an internally heated wafer holder or “chuck.” “Susceptors” are wafer supports used in systems where the wafer and susceptors absorb heat.
Some of the important controlled conditions for processing include, but are not limited to, pressure of the chamber, fluid flow rate into the chamber, temperature of the reaction chamber, temperature of the fluid flowing into the reaction chamber, and wafer position on the susceptor during wafer loading.
Wafers are loaded through vacuum valves into the chamber with a robot. During operation, the vacuum valves facilitate a separation between the wafer transfer regions and the processing region (the reaction chamber). Advantageously, the vacuum valve is a simple gate valve style device that may operate pneumatically, hydraulically, or by other suitable mechanism. Inevitably the reaction chamber will need to be serviced or cleaned. In some of these instances, it may be necessary or advantageous to keep the vacuum valve in place while performing maintenance. In these cases, it is unsafe because the vacuum valve may be operable and crush/sever a finger or limb.